The Problem of Corrosion and Tarnish of Dental Restorative and Implant Metals

Abstract

The linear polarization technique has been used to measure polarization resistances and corrosion currents directly in the mouths of baboons and in vitro for a wide range of dental and implant alloys. Good correlations were found to exist between these two conditions, indicating that this test is accurate and valid as well as being simple to perform. Intraoral corrosion proceeded faster, probably due to abrasion by foodstuffs. Tarnish has also been measured using an intraoral tristimulus colorimeter and results were compared with the corrosion determinations. The tarnish of pure metals (Au, Ag and Cu) was inversely proportional to corrosion. Gold alloys tarnished little but varied in corrosion current. Dental amalgams corroded the most but the tarnish experience depended more on their chemistry than their precious metal composition.